Retrogradation irreversible

The comparison between the two chain pairs is also consistent with the physical properties. Paramylon and amylose are known for their gel forming properties and their carbon reserve function in p1 ants.(13,69) Although (l- -3)-3-D-glucan also plays a structural rFTe when it occurs in the cell walls of yeast( ), it is probably more of a matrix substance than anything else. The ability to form multiple helices probably accounts for unusual solubility phenomena such as retrogradation( ) and irreversible gel formation on heating. (13)... 

With the aid of X-ray diffraction diagrams, native starches can be divided into t) es A, B, and C. An additional form, called the V-type, occurs in swollen granules (Fig. 4.26). While types A and B are real crystalline modifications, the C-type is a mixed form. The A-type is largely present in cereal starches, and the B-type in potatoes, amylomaize, and in retrograded starches (resistant starch, cf. 4.4.4.16.3). The C-type is not only observed in mixtures of corn and potato starches, but it is also found in various legume starches. When suspended in cold water, air-dried starch granules swell with an increase in diameter of 30 0%. If this suspension is heated, irreversible... 

Amylose gels tend to retrograde. This term denotes the largely irreversible transition from the solubilized or highly swollen state to an insoluble, shrunken, microcrystalline state (Fig. 4.31). This state can also be directly achieved by slowly cooling a starch paste. The tendency towards ret-rogradation is enhanced at low temperatures, es-... 

G.i Retrogradation F. rdtrogradation R. is the gradual and irreversible tendency of an aqueous starch dispersion or - modified starch dispersion to become insoluble during cooling, leading to a precipitate or a gel, depending on concentration and conditions. 

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